HARDENING CARBON STEEL FOR TOOLS

Restoring Overheated Steel
The effect of heat treatment on overheated steel is shown graphically
in Fig. 65 to the series of illustrations on pages 137 to 144. This
was prepared by Thos. Firth & Sons, Ltd., Sheffield, England.
The cente...

Hardening Carbon Steel For Tools
For years the toolmaker had full sway in regard to make of steel
wanted for shop tools, he generally made his own designs, hardened,
tempered, ground and usually set up the machine where it was to
be used and teste...

The Modern Hardening Room
A hardening room of today means a very
different place from the dirty, dark smithshop in the corner with
the open coal forge. There, when we wanted to be somewhat particular,
we sometimes shoveled the coal cinders ...

Take Time For Hardening
Uneven heating and poor quenching has
caused loss of many very valuable dies, and it certainly seems
that when a firm spends from $75 to $450 in cutting a die that
a few hours could be spared for proper hardening. ...

Carbon In Tool Steel
Carbon tool steel, or tool steel as it is commonly called, usually
contains from 80 to 125 points (or from 0.80 to 1.25 per cent)
of carbon, and none of the alloys which go to make up the high
speed steels. This wa...

Carbon Steels For Different Tools
All users of tool steels should carefully study the different qualities
of the steels they handle. Different uses requires different kinds of
steel for best results, and for the purpose of designating different
ste...

Steel For Chisels And Punches
The highest grades of carbon or tempering steels are to be recommended
for tools which have to withstand shocks, such as for cold chisels
or punches. These steels are, however, particularly useful where
it is neces...

Preventing Decarbonization Of Tool Steel
It is especially important to prevent decarbonization in such tools
as taps and form cutters, which must keep their shape after hardening
and which cannot be ground away on the profile. For this reason
it is well t...

Annealing To Relieve Internal Stresses
Work quenched from a high temperature and not afterward tempered
will, if complex in shape, contain many internal stresses which may
later cause it to break. They may be eased off by slight heating
without material...

Double Annealing
Water annealing consists in heating the piece, allowing it to cool
in air until it loses its red heat and becomes black and then
immediately quenching it in water. This plan works well for very
low-carbon steel; bu...

Quenching Tool Steel
To secure proper hardness, the cooling of quenching of steel is
as important as its heating. Quenching baths vary in nature, there
being a large number of ways to cool a piece of steel in contrast
to the comparativ...

The Theory Of Tempering
Steel that has been hardened is generally
harder and more brittle than is necessary, and in order to bring
it to the condition that meets our requirements a treatment called
tempering is used. This increases the to...

Temperatures To Use
As soon as the temperature of the steel reaches
100 deg.C. (212 deg.F.) the transformation begins, increasing in intensity
as the temperature is raised, until finally when the lower critical
range is reached, the s...

Knowing What Takes Place
How are we to know if we have given a
piece of steel the very best possible treatment?
The best method is by microscopic examination of polished and etched
sections, but this requires a certain expense for labora...

Hints For Tool Steel Users
Do not hesitate to ask for information from the maker as to the
best steel to use for a given purpose, mentioning in as much detail
as possible the use for which it is intended.
Do not heat the steel to a higher ...

Preventing Cracks In Hardening
The blacksmith in the small shop, where equipment is usually very
limited, often consisting of a forge, a small open hard-coal furnace,
a barrel of water and a can of oil must have skill and experience.
With this e...

Shrinking And Enlarging Work
Steel can be shrunk or enlarged by proper heating and cooling.
Pins for forced fits can be enlarged several thousandths of an
inch by rapid heating to a dull red and quenching in water. The
theory is that the metal...

Tempering Round Dies
A number of circular dies of carbon tool steel for use in tool
holders of turret lathes were required. No proper tempering oven
was available, so the following method was adopted and proved quite
successful.
Aft...

The Effect Of Tempering On Water-quenched Gages
The following information has been supplied by Automatic and Electric
Furnaces, Ltd., 6, Queenstreet, London, S. W.:
Two gages of 3/4 in. diameter, 12 threads per inch, were heated
in a Wild-Barfield furnace, usi...